Moreover, I noticed that 4.0.3_1 understood the deflogin and login screen commands (they are in my .screenrc) while 4.0.3_3 now complains about those. Also, my environment (set by .profile) is not kept when opening screens inside screen; so commands in .bashrc that depend on it, like PATH being set, started failing. I've had to add shell "-bash" to .screenrc to fix that, because it doesn't understand deflogin anymore.

For now; I'm staying on 4.0.3_1 until these issues are fixed.

Screen should understand deflogin and login, they are included in man screen.

There is no resolution for this ticket. Without that call, screen does not function in a very critical way - it doesn't persist if you log out. I'd consider that a much more important feature than being able to use pbcopy. Furthermore, this is fixed in SnowLeopard.

Does that mean that the patch that the situation is black or white? Either we apply the patch or we don't?
The whole point for this ticket is to find a middle way; applying the functionality introduced by the patch while not breaking the existing functionality which involves any communication between the terminal and apple utilities (this is definitely not a case of just pbcopy being broken).

The problem is with the behavior of launchd on Leopard. In essence, on Leopard, each login has its own separate launchd environment. On SL, it is per-user (thus you will share a launchd environment with your console login when you login via ssh or get a new login environment via screen). That is essentially the root of the problem here. If you're interested, Damien Sorresso gave a nice talk at WWDC this summer about the changes in SL's launchd. I believe either a webcast or slides may be available in Apple's dev-central...